Fluid dispenser pumps are well known in the state of the art, in particular for dispensing fluids, liquids, or pastes in the fields of cosmetics, perfumery, or pharmacy. They generally include a piston that slides in a pump body, more particularly in a pump chamber provided in the pump body, and that is adapted to dispense a dose of fluid each time the pump is actuated. The pump chamber generally includes an inlet valve so as to make it possible to define the dose of fluid expelled on each actuation. In addition, in particular with pharmaceuticals, pumps sometimes incorporate plugs for their dispenser orifices, so as to avoid any contamination of the fluid between two actuations.
A problem that occurs with that type of pump relates to priming. Before the pump is actuated for the first time, the pump chamber is full of air, and it is thus necessary to expel all of the air so as to enable said pump chamber to be filled with fluid, and so as to enable accurate and reproducible metering each time the pump is actuated. Priming is made all the more complicated when the pump includes a plug. It is difficult to expel the air contained in the pump chamber out from said pump chamber, in particular because of the presence of said plug.
Another problem that can occur with fluid dispenser pumps relates to the quality of the spray, when said pump is a spray pump. Particularly when a plug is provided for the dispenser orifice, the quality and the characteristics of the spray during expulsion depend on said plug. Unfortunately, since most plugs are moved by the fluid pressure created during actuation, actuations with different intensities or axial forces can cause the characteristics of the spray to change. In particular in pumps in which the plug moves axially away from the dispenser orifice during actuation of the pump, too great a displacement of said plug risks causing a loss in the quality of the spray, and consequently poor dispensing of the dose.
Another problem that can also occur with fluid dispenser pumps relates to the risk of the pump becoming blocked. In particular, this risk can occur with so-called “airless” suction pumps if the suction in the fluid reservoir exceeds the suction that the pump or metering chamber is capable of generating when the pump returns to its rest position after actuation. The inlet valve of the pump chamber can thus become blocked, thereby blocking the pump as a whole. In this event, the natural suction capability of the pump is insufficient to counter the suction from the reservoir, if the suction level is not always relayed to the pump chamber after each actuation. Unfortunately, as a pump is used, some of its component parts, generally those made of plastics material that is more or less rigid, risk deforming naturally under the effect of the suction, and are thus likely to generate this disadvantageous increase in reservoir suction relative to pump-chamber suction.
An object of the present invention is to provide a fluid dispenser pump that does not have the above-mentioned drawbacks.